Here is a link to the guidelines to servicers from Fannie Mae...
https://www.efanniemae.com/sf/guides.../2009/0905.pdf all the items in bold are changes to the original guidelines that were previously announced. Pay particular attention to the eligibility criteria and the statements regarding the NPV test. Since you have confirmed that your loan is backed by Fannie Mae, I cannot see any reason that you would not qualify (barring any of the listed exceptions). Also check out the resources listed here (this is where I've found a great deal of useful information):
https://www.efanniemae.com/sf/mha/mhamod/index.jsp
I filled out the hardship affidavit that is listed here:
https://www.hmpadmin.com/portal/mod_docs.html
I had my local HUD office send this affidavit in requesting that BofA review my case a second time based on my husband's raise. I looked up my loan info online at BofA last night and under workout information, it does show another workout letter processed on 6/29 so it would appear that the HUD office did as promised. I am not working with NACA but rather my local HUD agency. If you don't have any luck with NACA, look up your local HUD office and see if they can assist you. Hope this information is helpful. Be persistent and don't give too much weight to anything the customer service people tell you (they really aren't all that informed).
Best of luck!